cc: Cleanup class/struct forward declarations

cc/debug/rasterize_and_record_benchmark_impl.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_IMPL_H_
 #define CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_IMPL_H_
 
 #include <stddef.h>
 
 #include <map>
 #include <utility>
 #include <vector>
 
 #include "base/single_thread_task_runner.h"
 #include "base/time/time.h"
 #include "cc/debug/micro_benchmark_impl.h"
 #include "cc/raster/task_graph_runner.h"
 
 namespace cc {
 
 class LayerTreeHostImpl;
 class PictureLayerImpl;
-class LayerImpl;
+
 class RasterizeAndRecordBenchmarkImpl : public MicroBenchmarkImpl {
  public:
   explicit RasterizeAndRecordBenchmarkImpl(
       scoped_refptr<base::SingleThreadTaskRunner> origin_task_runner,
       base::Value* value,
       const MicroBenchmarkImpl::DoneCallback& callback);
   ~RasterizeAndRecordBenchmarkImpl() override;
 
   // Implements MicroBenchmark interface.
   void DidCompleteCommit(LayerTreeHostImpl* host) override;
@@ skipping 15 matching lines @@
     int total_picture_layers_off_screen;
   };
 
   RasterizeResults rasterize_results_;
   int rasterize_repeat_count_;
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_RASTERIZE_AND_RECORD_BENCHMARK_IMPL_H_